Power supply control circuit with optical feedback

Abstract

An integrated circuit is disclosed that integrates a low current, high speed optical receiver with the primary side control functions of the power supply. This is further combined with an optical emitter to create a single component for feedback and control, providing improved performance and manufacturing. A method of providing feedback for the power supply using such an integrated optically coupled control circuit is also disclosed.

1. A silicon integrated circuit for controlling a power supply, comprising:
 a photodiode for receiving an optical feedback signal; 
 a transimpedance amplifier which converts current in said photodiode to a control signal responsive to said feedback signal; 
 a pulse controlling circuit for generating pulses in response to said control signal; and 
 a driver circuit for controlling a power transistor wherein said transimpedance amplifier, said photodiode, said pulse controlling circuit, and said driver circuit are directly integrated onto a chip. 
 
   
   
     2. The integrated circuit of  claim 1  wherein said optical feedback signal and said control signal are continuous analog signals. 
   
   
     3. The integrated circuit of  claim 1  wherein said optical feedback signal and said control signal are pulsed signals. 
   
   
     4. The integrated circuit of  claim 1  wherein said power transistor is integrated into said integrated circuit. 
   
   
     5. The integrated circuit of  claim 1  wherein said pulse controlling circuit comprises
 an oscillator providing a clock signal at a substantially constant switching frequency; and 
 a pulse modulating circuit providing pulses at said substantially constant frequency of said clock signal and at a pulse width responsive to said control signal. 
 
   
   
     6. The integrated circuit of  claim 1  wherein said pulse controlling circuit comprises:
 an oscillator providing a clock signal at a substantially constant switching frequency; and 
 a pulse modulating circuit providing pulses at said substantially constant frequency of said clock signal and at a pulse width responsive to said control signal and to instantaneous current flowing in said power transistor. 
 
   
   
     7. An optocoupled component comprising:
 the integrated circuit of  claim 1 ; 
 a light emitting diode (LED); 
 a package providing electrical connection to said integrated circuit and said light emitting diode, and an optical path to allow light from said light emitting diode to couple to said photodiode of said integrated circuit.